1. Field of the Invention
This invention relates to a sandwich glass usable for use in a front glass and a side glass of an automobile, a window glass of a building and the like.
2. Related Art Statement
In general, polyvinylbutyral resins have hitherto been mainly used as an intermediate layer for the sandwich glass. However, such a polyvinylbutyral resin is thermoplatic, so that it has the following drawbacks:
(1) Since the polyvinylbutyral resin has a relatively low softening point, the sliding of glass plates or formation of bubbles in the sandwich glass occur due to heat after the glass plates are stuck to the resin;
(2) Since the polyvinylbutyral resin is apt to be influenced by moisture, when the sandwich glass is left to stand under a high humidity atmosphere over a long period of time, the resin gradually whitens from the peripheral portion of the sandwich glass and also the adhesion force to the glass plate is reduced; and
(3) The impact fracture resistance of the sandwich glass is dependant upon temperature, and particularly the penetration resistance rapidly decreases at a temperature region exceeding room temperature, that is, at a temperature not lower than about 30.degree. C.
In order to solve the above drawbacks of the polyvinylbutyral resin, the inventors have previously proposed a sandwich glass obtained by interposing a thermosetting resin comprised of ethylene-vinyl acetate copolymer and an organic peroxide between glass plates and then conducting the thermosetting of the resin (Japanese Patent laid open No. 57-196747).
Considering a safeness as a great requirement of the sandwich glass, the impact resistance and the penetration resistance could not be said to be sufficient under wide conditions even in the inventors's previous inventions.